Electro-hydraulic actuator

ABSTRACT

This present invention relates to a remote electro-hydraulic actuator for actuating of mechanical devices, such as a valve in an internal combustion exhaust pipe. The actuator includes a multi-vane rotational assembly that flows the working fluid through strategically sized flow channels within the structure of the rotational assembly. The size of the holes are sized to help the stability of the valve and can also be provided with pressure check valves or reed valves to dampen the rotation of the valve and reduce any instabilities due to pulsations driven back via the output shaft.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/471,410 filed Aug. 28, 2014 and entitled “ Remote Electro-HydraulicActuator.” application Ser. No. 14/471,410 claims priority to and thebenefit of U.S. Provisional Application No. 61/871,564 filed Aug. 29,2013. The entire content of these applications are herein incorporatedby reference in their entirety.

FIELD OF THE DISCLOSURE

The present invention relates to a remote electro-hydraulic actuator. Inparticular, the invention relates to an actuator for actuating andcontrolling a valve.

BACKGROUND

Industrial, residential and mobile, including power generation,transportation, automotive and aerospace, controls systems often requireactuation of mechanical components. Mechanical components of suchsystems may include valves that must be actuated. Such actuation isgenerally accomplished via pneumatic, hydraulic or electric componentsand/or systems. There are generally three different remote controlledtypes of valve actuation.

Valve actuation may be accomplished by electric components, includingpermanent magnet direct current (PMDC) motors, brushless direct current(BLDC) motors, direct current stepper motors, linear or rotarysolenoids. Electric actuation is susceptible to environmentaltemperatures and suffers from reliability issues, especially in mobileapplications due to the variations in operating environment and theharsh engine compartment/under hood environment.

Valve actuation may also be accomplished by pneumatic orelectro-pneumatic means using pneumatically controlled linear or rotaryactuators. Such actuators may include on/off or proportional actuation.Pneumatic and electro-pneumatic systems suffer from low positionaccuracy due the compressible nature of the fluid, typically atmosphericair, used for actuation and the moisture generated in the air compressorsystem.

In addition, valves in mechanical systems may be actuated byelectro-hydraulic means, using hydraulically controlled linear or rotaryactuators. Such actuators may employ on/off or proportional control.Conventional electro-hydraulic actuators use oil from the enginelubricating system or other high-pressure hydraulic power assistsystems. The pressures of the engine lubricating systems are in theneighborhood of 100 psi and vary with engine speed.

BRIEF DESCRIPTION OF THE PRIOR ART

Electro-hydraulic actuators are known in the prior art, For example,U.S. Pat. No. 7,419,134 to Gruel is titled “Valve Actuation Assembly.”European Patent Publication No. EP 0 248 986 to Vick et al. is titled“Rotary Vane Hydraulic Actuator.” U.S. Pat. No. 5,007,330 to Scobie etal. is titled “Rotary Actuator and Seal Assembly for Use Therein, U.S.Pat. No. 6,422,216 to Lyko et al. is titled “Exhaust Gas RecirculationValve.”

APPLICATION OF THE INVENTION

Embodiments of the invention may be used, for example in automotive,aeronautical, rail or other transportation applications of internalcombustion engines. In order to minimize pollutants produced by internalcombustion engines, a portion of the engine exhaust may be recirculatedto an intake of the engine. An exhaust gas recirculation (EGR) valve,such as a mixing valve, may be used to assist in directing the portionof the exhaust to the intake. Such valves typically require a great dealof torque for actuation during engine operation. In addition, suchvalves are often disposed within the engine compartment and, thus,require compact actuation assemblies due to space constraints

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a single vane rotary actuator as isknown in the prior art.

FIG. 2 shows a perspective view of a piston rotary actuator as is knownin the prior art.

FIG. 3 shows a cross-sectional view of the piston rotary actuator ofFIG. 2.

FIG. 4 shows a perspective view of a valve and actuator in accordancewith embodiments of the present invention.

FIG. 5 shows a top view of the valve and actuator of the embodiment ofFIG. 4.

FIG. 6 shows an exploded view of a valve assembly according to anembodiment of the invention.

FIG. 7 shows and exploded view of an actuator assembly according to anembodiment of the invention.

FIG. 8 is a perspective view of the actuator assembly of FIG. 7.

FIG. 9 is a perspective view of an actuator main housing according to anembodiment of the invention.

FIG. 10 shows a top view of a vane rotational assembly according to anembodiment of the invention.

FIG. 11 shows a perspective view of the vane rotational assembly of FIG.10.

FIG. 12 is a partial cross-sectional view of an actuator assembly inaccordance with an embodiment of the invention.

FIG. 13 is a cross-sectional view perpendicular to the rotational axisof an upper actuator assembly cover in accordance with an embodiment ofthe invention.

FIG. 14 is a cross-sectional view parallel to the rotational axis of anupper actuator assembly cover in accordance with an embodiment of theinvention.

FIG. 15 is a second cross sectional view of the upper actuator assemblycover of FIG. 14.

FIG. 16 is a perspective view of a lower actuator assembly cover inaccordance with an embodiment of the invention.

FIG. 17 is a perspective view of an upper actuator assembly cover inaccordance with an embodiment of the invention.

FIG. 18 is a perspective view of a spool valve as used in embodiments ofthe invention.

FIG. 19 is a perspective view of the upper actuator assembly cover ofFIG. 17.

FIG. 20A is a flow diagram of a parallel cooling circuit in accordancewith an embodiment of the invention.

FIG. 20B is a flow diagram of a series cooling circuit in accordancewith an embodiment of the invention.

FIG. 20C is a flow diagram of an independent cooling circuit inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION

There are several design variants of rotary electro-hydraulic actuatorsas known in the prior art and shown in FIGS. 1-3. FIG. 1, for exampleillustrates a single vane rotary actuator. Such an actuator 100 includesa base or lower cover 102. A housing 104 with a cylindrical interiorextends from the lower cover. An upper cover (not shown) covers theother end of the housing 104. The actuator 100 further includes arotational assembly 106, which includes a hub 108 and a vane 110. Inaddition, the actuator includes a partition wall 120. The vane inconjunction with the partition wall divides the interior of the housinginto two chambers 112, 114. The actuator also includes an input port 116and a return port 118. Accordingly, when hydraulic fluid is pumped intothe actuator through the input port 116 and fluid is allowed to exitthrough the return port, the actuator will rotate in a first direction.When fluid is pumped into the actuator through the return port 118 andfluid is allowed to exit through the input port, the actuator willrotate in the opposite direction. A shaft 122 extends from the hub 108to transfer torque to the device to be actuated. The flow direction andrate are controlled via a remote or onboard control valve. These areusually spool valves or poppet valves.

FIGS. 2-3 illustrates an alternative electro-hydraulic actuator as knownin the prior art using a cylinders 202, 204 and pistons 206, 208connected by a rod 210. The rod 210 includes teeth 214 that engage withteeth 216 on a rotating member 218. In such a system, the hydraulicpressure is applied to one or the other piston through ports 220 or 222.This causes the rod 210 to translate, which imparts rotational motion tothe rotary member 218. This rotary motion can be output from theactuator via a hub 224.

In almost all rotary applications the valve is of the single vanedesign, such as shown in FIG. 1. However, in such actuators, the torquethat the actuator is capable of producing is proportional to theeffective surface area of the vane. In order to increase the availabletorque, the vane surface area, and thus the size of the actuator must beincreased. Accordingly, it may he advantageous to utilize an actuatorhaving more than one vane. For example, using two vanes effectivelydoubles the available torque without increasing the overall size of theactuator. Provided, however, that increasing the number of vanes allowsfor increased torque by increasing the vane areas but with a reductionof the range of rotational movement of the actuator. A single vaneactuator has a potential rotational capability of about 300 degrees,depending of the chamber partition wall and vane thickness, while atwo-vane actuator rotation have about 150 degrees and a three vaneactuators has about 80 degrees rotation, etc.

One of the major challenges of a multi-vane rotary actuator is to routethe pressurized hydraulic fluid to the input and output ports of theactuator. For example, when the valve is commanded to move clockwise,one (or more) chamber(s) is pressurized while another one (or more)chamber(s) is discharged to a reservoir. The routing of the fluids maybe controlled via a multipart spool valve but the required input andoutput passages required to be routed from the spool valve to thechambers can be complex and requiring a multi-way spool valve optionsthat are expensive and significantly increase the overall size of theactuator. Embodiments of the present invention address this and otherdeficiencies of the prior devices.

FIGS. 4-5 illustrate a valve assembly 301 and actuator 308 in accordancewith embodiments of the present invention. A butterfly valve plate 302is positioned within a valve housing 304. The valve housing may beinstalled in the exhaust system of an internal combustion engine. Thebutterfly valve plate 302 may be opened and closed to control the flowof fluid through the housing 304. Support posts 306 extend from anoutside surface of the housing. The support posts may he used to mountan actuator 308. The posts may also provide thermal insulation for theactuator assembly, protecting it from the heat of the exhaust gasespassing through the housing 304.

In addition, insulating washers 310 may be mounted on posts 306 tominimize the conductive heat transfer. Other means of minimizingconvective and radiant heat transfer into the actuator is making the useof heat shields. These heat shields can be in for of single-walled ormulti-walled designs containing insulating materials or just relay on anair gap. Alternatively, other mounting means may be used to secure theactuator 308 to the valve housing 304. Additionally, the lower cover314, housing 318 and upper cover 312 may include holes 322 (see FIG. 7)that provide a means for securing the actuator 308 to the posts 306 andthe valve assembly 304. For example, bolts 323 (shown in FIG. 4) may beinserted through holes 322 into posts 306. In the illustratedembodiment, the actuator assembly is attached to the flow modulatingdevice, valve 301, via four M10 bolts 323. Depending on the geometricshape and size of the actuator the number of bolts can be reduced innumber or changed in size.

FIG. 6 illustrates an embodiment of the valve assembly 301. The valve inthis embodiment is a butterfly valve. The main function of the butterflyvalve described in this embodiment is to modulate fluids in internalcombustion engines. Although references are made that the butterfly isbeing used on internal combustion engines it can be used to controlfluid flow for many applications, ranging from engines, industrial andresidential fluid control systems. These fluids can be cold or extremelyhot. In certain applications gaseous exhaust temperatures reachtemperatures in excess of 800° C. and careful selection of the alloys isrequired. Modulating sealing surfaces, shaft journals and bearings andshaft seals are the major wear components of the valve and high nickeland cobalt alloys are required. In the case of this embodiment, abutterfly valve is being described because of its pressure balancingcharacteristics but flap valves can also be considered for this actuatorapplication.

The illustrative valve assembly 301 includes a main valve housing 304. Ashaft 332 extends through a sidewall into the interior of the housing304. The valve assembly further includes a butterfly plate 406positioned inside the housing 304. The butterfly plate 406 includesfirst and second vanes 330 extending in opposite directions. Thebutterfly plate is connected to a shaft 332 that extends through thesidewalls on opposite sides of the housing. The shaft 332 may extendbeyond the house wall on the side adjacent the actuator 308 in order toengage with a hub of the actuator. The butterfly valve vanes 330 may beconnected with the shaft 332 by fasteners 334, such as retention screws.The valve assembly may also include bushings or bearings 408 and a shaftend cap 412. The end cap may be secured to the housing 304 by screws 413or other fasteners in order to secure the shaft 332 in position. Thevalve can be configured to attain a normally open or a normally closedbutterfly valve condition by adjusting the vane assembly or switchingthe hydraulic input/output ports.

The actuator of the present invention is not limited to use with thebutterfly described herein. In addition to a butterfly or flap valve,embodiments of the actuator may be used with any flow-modulating device,including for example single or multiport gate valves, globe valves,disk valves, stem valves, or other appropriate valves. In addition, theactuator may be used in rotational and linear mechanical motion devices.The actuator may be used in any device that can accept rotational motionas an input, including devices where rotational motion is transformedinto linear or other motion by screws, linkages, gear trains,rack-and-pinion assemblies, etc.

Embodiments of the actuator 308 are illustrated in FIGS. 7-8. The mainfunction of the actuator is to position the fluid modulating valve 301according to the required engine control parameters. The actuatorrepresented in this embodiment is a dual vane design and has a totalrotational travel of 85 degrees. Other vane configurations or rotationaltravel would be apparent to one of skill in the art.

The actuator 308 may comprise a housing 318. The housing is sealed by anupper cover 312 and a lower cover 314. However, while this and otherembodiments described herein illustrate an actuator assembly having ahousing with separate upper and lower covers, it should be understoodthat two or more of these components may be formed as a single piece.For example, the housing and upper cover may be formed as single piece,or the housing and lower cover may be formed as a single piece.

Embodiments of the actuator may also include a vane 504 for rotationwithin the housing 318. The vane 504 may rotate on a bearing 508 andmain include vane tip seals 522. The housing 318 and covers 312, 314 mayalso incorporate housing seals 510 to better seal between thecomponents. In addition, a main shaft seal assembly 514 may he used toseal against the shaft 332 extending from the valve assembly 301. Theshaft 332 may also engage with a standalone shaft sensor or contain partof the shaft positioning sensor assembly when used in conjunction with ashaft position sensor 518 and/or an electronic control circuit board 519positioned beneath a cover 517.

Single or multiple actuator control valves may he used in theapplication. The valve may be a two-way/two-position cartridge spoolvalve with a proportional design or any other appropriate valve. Thevalve may be incorporated into the upper cover 312 or into the lowercover 314 and fluid may be routed to chambers of the actuator asrequired. Alternatively, the valve may be incorporated into the side ofthe actuator. The control valve 516 may he coupled to fittings 327, 328for connecting with a hydraulic pump of the hydraulic system or apneumatic pump if a pneumatic system is used.

As shown in FIGS. 7-8, the upper cover 312, housing 318 and lower cover314 may include through holes 320. Bolts, screws or other fasteners 321may be inserted into these holes 320 in order to secure the covers 312,314 to the housing 318. In the illustrated embodiment, these fastenersinclude eleven M6 bolts. Depending on the geometric shape and size ofthe actuator the number of bolts can be reduced in number or changed insize. The holes 320 may be internally threaded or may provide otherfeatures that contribute to securing the components. The actuator 308may have a generally central axis 324 about which the rotationalassembly of the actuator rotates. The upper cover 312 may havereinforcing struts 326.

As shown, by example, in FIG. 7, a bottom cover 314 of an actuator 308may include an opening 336. A hub 338 of the rotational assembly of theactuator may be exposed through the hole. As shown in FIG. 9, the hub338 may include a female socket 340 recessed into the huh. The socket340 may include splines 342 that engage with splines 333 formed on shaft332. The splines can be arranged symmetrically around the wholecircumference or can be asymmetric or lost tooth format. The hub can bedesigned of any alloy, but given the tendency of high torque requirementand high temperature applications, the alloy selected will be of lowheat conducting, high toughness and low wear characteristics.

FIG. 9 depicts an embodiment of the actuator main housing 318 and vanerotational assembly 648. The depicted main housing consists of anextruded aluminum profile that attains near net shape conditions.Although other manufacturing processes such as die casting, forging,etc. can be used for this part, extruded aluminum profile provide nearnet shape parts that do not require major post manufacturing processes,offer dimensional stability and high physical properties. Extrudedaluminum alloys also can be easily coated or plated with wear reducingand low friction coatings and plating.

The internal profile is designed to contain the travel end stops 612 andsealing surfaces 614 of the rotating vane 504. Corner radii 604 of theinternal profile are shaped to allow for any secondary profile clean upusing robust machining tools. Passages for assembly bolts 606,attachment screws 607 and coolant routing 608 are extruded to minimizethe post machining processes.

The extrusion design option also allows the sizing of the actuator. Thetorque capabilities of the actuator are directly proportional to thearea exposed to the pressurized working fluid. The area is a function ofthe diameter and length of the vane 504, and thus extrusion generates aneasy option to cut the actuator length within the extrusion length. Thelength of the actuator 610 is partially restricted by the packagingconstraints but in general range from 25 mm to 75 mm. The actuator vanedepicted in this application is 35 mm length to achieve the specifiedtorque characteristics of 40 Nm of torque.

The main housing depicted in FIG. 9 can be configured to house theworking fluid inlet and outlet ports 327, 328 and the electric hydrauliccontrol valves. Although inlet and outlet ports depicted are of theexternal flare style and of different size to eliminate assembly mistakethey can be of any size, type and gender to achieve the requiredconnection point and mistake proofing.

The actuator main housing is for a dual vane actuator design hut theextrusion profile could be designed into any shape to achieve fromsingle to multi vane actuator design with the gain in torque output butwith loss of rotational range. As shown in FIG. 9, the housing has agenerally cylindrical inner cavity, Partition walls 644 extend from aninner surface 646 of the cavity. A rotational assembly 648 is positionedfor rotation about a central axis of the actuator housing. Therotational assembly includes a hub 338 with a first vane 654 and asecond vane 656 extending from the hub.

To minimize internal leakage, the tip of the vanes 654 and 656 can besealed against the inner surface 646 of the housing 31 by tip seals 614or by using tightly toleranced parts and thermal conductive matched.Chamber seals 662 seal the ends of partition walls 644 against hub 338.In addition, housing seals are fitted into grooves 664 in order to sealupper and lower covers to the housing 318. In addition, bearings (notshown) may be utilized to facilitate rotation of the rotational assembly318. The bearings may be deep groove bearings.

FIG. 10 depicts a vane rotational assembly configuration used in anembodiment of the invention. Main functions of the vane in thisapplication are to house the bearings, serve as the working fluidmanifold, transmit rotational motion to device to be driven shaft andseal the working chambers. The seals can be of various types: forceactivated wiper seals and labyrinth style seals.

The area of the actuator vane exposed to the pressurized working fluiddetermines the performance to of the actuator assembly. In multi-vaneactuator applications one of the main challenges is the routing of theworking fluid to and from the required chambers and itsmanufacturability. Embodiments of the vane actuator may be manufacturedby various methods, including extrusion and investment casting. Vanecommunication passages or manifolds 702, 703 are depicted in FIG. 10.These passages can be achieved via investment casting, 4-axis electricaldischarge machining (EDM) or cross drilling. Spark eroding thecommunication channels with a 4 axis EDM process is slow and expensiveand challenged by the line of sight and passage size restricted by thevane interior diameter feature that connects to the output shaft of theshaft from the device to be driven. Investment casting allows the optionto cast the passages in circumferential geometry and allows fornon-circular cross-section allowing the flow to be maximized. Specialcores and core support have been designed to achieve this configuration.

The size and the geometry of this passage control the performance of thevalve. Smaller holes or inserted orifii may restrict the fill of thesecondary chambers while inserted check valves can time the fill of thesecondary chambers. The flow area of the communication passages can be10 to 50 mm² but in general are sized to 30 mm² as depicted in thisembodiment to adapt commercially available check valves.

In the case of investment casting and extrusion, which are of the nearnet shape manufacturing processes, features 704 are formed into the vanegeometry to minimize the final machining process and help in the use ofhighly robust cutting tools to minimize the manufacturing process cycle.Undercut areas 706 in the vane to hub area may be used to eliminate theneed to use very small diameter contouring tools as well as serve as thestarting edge for the cross drilling, 4-axis EDM or press feature forthe check valves or orifii.

Sealing of the working chambers may be achieved with vane tip sealsinserted into channels 710 formed at the tip of vanes 712, 713 and hubradial seals 708. These seals can be dynamic seals like labyrinth sealsor force activated static seals. Force activation is mainly achieved viaelastomers or metal springs while the wiping element is a low frictionchemically inert compound such as a polytetrafluoroethylene (PTFE)material, for example TEFLON.

FIG. 10 depicts an internally supported vane via the bearings toward thehub extensions in the covers, externally supported vane is also possiblebut such a design does not allow for minimized packaging.

As illustrated in FIG. 10, an actuator in accordance with embodiments ofthe present invention flows the working fluid through strategicallysized flow channels 702, 703 within the structure of the vane assembly.The ports and passageways are sized to provide dampening and improve thestability of the valve and can also be provided with pressure checkvalves or reed valves to dampen the rotation of the valve and reduce anyinstability due to pulsations driven back via the output shaft.

For example, vane 713 may include a port 723 formed in a first face 733of the vane. The port 723 is connected via an internal passageway ormanifold 703 to a port adjacent the opposite face 752 of the second vane712. Likewise, a port 722 on the first face 732 of the vane 712 isconnected via an internal passageway or manifold 702 to a port 743 onthe opposite face 753 of vane 713.

In this manner, a pressurized flow of hydraulic fluid is applied to face733 of vane 713 inducing the assembly to rotate in a clockwisedirection. The fluid then passed through the body of the actuatorassembly, through passageway 703. The hydraulic fluid then appliespressure, to the opposite face 752 of vane 712 increasing the clockwisetorque on the assembly. In a like manner, return flow applies a force tothe face 753 of vane 713 to rotate the assembly in a counterclockwisedirection. The return flow of fluid passed through passageway 702. Thehydraulic fluid then applies pressure to the face 732 of vane 712increasing the counterclockwise torque on the assembly. Flow from theprimary chamber to the secondary chambers can be delayed or dampened bythe use of orifices and/or check valves 715, 717. The valves 715, 717may be pressure relief valves. The use of such devices can increase theaccuracy of the actuator and dampening characteristics due to the torquefluctuations imparted on the output shaft.

As illustrated in FIGS. 9-10, embodiments of the invention may use atwo-vane rotational assembly. The assembly includes a hub 762. Vanes 712and 713 extend from the hub. In this embodiment, the vanes are offset atan angle less than 180 degrees in order to accommodate flow channels andvalves in the actuator housing. The angle between the vanes will affectthe maximum rotation of the actuator and may be any appropriate angle upto 180 degrees. Alternatively, the vane rotational assembly may havemore or fewer vanes. The rotational assembly may be formed from multiplecomponents joined together by known means. Alternatively, some or all ofthe components may be formed from as a single piece.

The support of the rotating members of this valve can be external orinternal to the shaft/vane assembly. The use of shaft support in theform of ball bearings, needle bearings, bushings exclusively orcombination thereof can generate packaging and cost advantages.

As illustrated in FIGS. 10-11, embodiments of the vane assembly includea hub 762. Vanes 712 and 713 extend from the hub. A socket 740 isrecessed into hub 762 for engaging a shaft extending from the device tobe actuated. The socket 740 may include splines 745 for engagingcorresponding splines on the device shaft. A bearing surface 749 may beformed on a surface of the hub 748 in order to engage with a bearing 750for rotational movement.

FIG. 12 is a cross-sectional view of an actuator assembly of anembodiment. The actuator assembly includes an upper actuator cover 802and lower actuator cover 804. A function of the covers is to seal theworking chambers 806 of the main housing, guide the vane rotation viathe cover extension shafts 808, 809 and route the coolant as depicted inFIGS. 13-15. As illustrated in FIGS. 13-15, the upper cover 802 mayinclude closed channels 812 drilled, casted (lost foam invested casting,etc.), formed or cut into the cover. These cooling channels can bemachined or cast into the upper cover alone, lower cover alone or intoboth. The requirement is dictated by the source of the heat: conductive,convective or radiant. Hydraulic fluid provided by a hydraulic pump maybe passed through these channels. For example, bypass fluid not used toactuate the actuator may be passed from the pump through the channelsbefore being returned to a reservoir. This fluid may be used to cool thebottom cover and thus provide thermal insulation for the actuator 308.Although the cooling circuit described in this invention makes use ofthe existing working fluid, either in parallel or in series circuits,the cooling circuit can also be an independent cooling system whereengine coolant or any other cooling fluid can be used. As illustrated inFIG. 20A, working fluid may exit the working fluid reservoir 903 andpass in parallel through the primary chamber 905 and cooling circuit907. As illustrated in FIG. 20B, working fluid may exit the workingfluid reservoir 903 and pass in series through the primary chamber 905and cooling circuit 907. Alternatively, as illustrated in FIG. 20C, aseparate working fluid reservoir 903 and cooling fluid reservoir 909 maybe used with independent cooling systems such that cooling circuit 907is not fluidly connected with the flow of fluid through the primarychamber 905.

The origin of the oil can either be from diverting the supply line orpassage, and flow may be determined by the amount of oil flow to achievethe cooling action. Sizing of the flow channel, by the use of castingtechniques, inserted orifices, etc., determines the flow according thepressure available. Flow can also “timed” via a check valves that cutthe diverted cooling oil flow at low oil pressure conditions. Oilpressure is directly related to engine load and thus to the temperaturesin the exhaust, i.e. at idle where oil pressure is low (e.g. 20 psi)cooling flow is not required because exhaust gas temperatures are fairlylow and do not affect the performance and durability of the actuator.

The cover 802 may have an inlet port 814 formed in an inside surface 818of the cover that receives hydraulic fluid flowing though the valve andhousing of the actuator. The fluid then passes through channels 812formed in the cover. The fluid then exits through a port 816. Inlet port814 and outlet port 816 may be located at the cross over ports in theactuator housing. The cooling channels may create a cooling curtain thatis sized to achieve the maximum surface area. The upper cover 802 mayhave an opening 838 through which the huh or shaft of the rotationalassembly may be exposed.

Cooling flow may be made through the upper cover. Alternatively, thecooling flow can also pass through the main body or lower cover. Or theflow may pass through multiple or all of these portions depending whichpart of the actuator may benefit from being he cooled or protected.These flow passages can be in the form of drilled, caste or formedpassages or rerouted by external conduits such as hoses and tubes.

As shown in FIG. 12, the upper cover in addition to above mentionedfunctions may also contain electronic control circuitry,electric/electronic input/output circuitry 902 and/or a shaft positionsensor 904. The shaft position sensor may be a standalone sensor. Theelectronic control circuitry may comprise a printed circuit board, andthe printed circuit board may be rigid at least in part and/or flexibleat least in part. An additional function of the lower cover is to housea main shaft seal 906, house additional sealing components 908 thatcontain minute exhaust leaks during extreme engine transients and serveas a structural interface to the valve or other device to be driven, forexample through support posts 910. Although the figure depicts coverswithout any control valves, the castings can easily be designed tocontain the fluid control valve.

As depicted in FIG. 16, lower cover, and FIG. 17, upper cover,embodiments of the invention include a configuration in which routingand control of the coolant circuitry is positioned within a single-piecealuminum component. This unique design allows for one casting that fitsmultiple applications and that provides both lower and upper covers. Thelower and upper raw castings or forgings are designed to be common andthen machined according to the application. Machining variation cangenerate many different variants of the actuator according to itsapplication, including: a smart drive by wire actuator, a passiveactuator. For example, the lower cover 804 shown in FIG. 16 use the samecasting as the upper cover 804 of FIG. 17. The cover 802 may then beprocessed or machined to create an opening 836 to accommodate a shaftseal and become the lower cover. The cover may be processed to have anopening 838 that may accommodate sensors or other control circuitry andthus become an upper cover. In this way, the actuator may be internallycooled, top cooled or bottom cooled. It may also use fluid or gaseouscooling, serial or parallel cooling or no cooling. Such a symmetricconfiguration also has advantages for manufacturing tooling cost, onlyone casting or forging tool is required. The coolant circuit can bepresent in the upper or lower cover or both depending of theapplication. Aluminum lost foam, investment casting, forging and brazed,billet machined and brazed processes may be the processes of choice forthis design but is dependent on production volume.

As shown in FIGS. 18-19, in embodiments of the present invention,directional and modulating control of the working fluid from one chamberto another of the actuator may be controlled via an electronicproportional solenoid 916. Although hydraulic and pneumatic fluids arediscussed in this application, any compressible or non-compressiblegases and liquids can be used as the working fluid. The proportionalsolenoid can be of the push, pull or dual actuated style. The modulationcan be achieved via a single multiport spool valve, multiple dual portspool valve or pairs of proportional poppet valves. As shown in FIG. 7,embodiments of the invention may include a control system 515 that usesthe valve 516, whether proportional, poppet or other, to maintain theposition of the actuator. For example, the control system may includeone differential or two absolute pressure sensors 521 to sense thedifferential pressure across the two chambers. The control systemperiodically compares the pressure. If the control system detects apressure differential, the system compensates by appropriatelyincreasing or decreasing the fluid in the chambers. This balancing offluid pressure between the chambers is accomplished using one or more ofthe valves as described. In this manner, the actuator can maintain theposition of the actuator and thus the valve or other device being drivenby the actuator.

Sizing of the ports and number of valves determines the response time ofthe actuator and the pressures losses that directly results in the lossof torque. The valve size may vary as appropriate for the application aswould be understood by one of ordinary skill in the art. The actuatorcan be configured with the proportional solenoid valve in the uppercover, main actuator housing or lower cover. The solenoid depicted inFIG. 18 is designed to be installed in the actuator main housing due topackaging constraints and to reduce the overall size of the actuatormechanism.

The proportional valve(s) can contain mechanical position feedback orelectronic position feedback. In the case of mechanical feedback thespool of the valve is biased via a spring cam mechanism to attain andmaintain the commended position. If electronic position feedback isused, Hall effect or similar sensors are being used to obtain spoolposition feedback. In an alternative embodiment, pressure feedback fromthe actuator working chambers may be used in commanded positioning andto aid in the critical dampening of the actuator/valve. These types offeedback maybe used to attain and maintain the spool position, whichcontrols the actuator shaft position.

In embodiments of the invention, the position of the actuator is drivenby the actuation of a proportional cartridge valve through an analog,pulse width modulated (PWM) or digital signals generated by an EngineControl Unit (ECU). The system can further be augmented withelectronic/hydraulic logic to increase the self-sufficiency of the valvesuch as position, response time, etc.

In accordance with embodiment of the invention, it may be desirable toprovide information regarding the rotational position of the rotatingassembly such as the rotational position of the output shaft 332 shownin FIG. 6 or the female socket 340 shown in FIG. 9. Such positionfeedback can be open loop or closed loop type. Open loop feedbackdepends only on the command control of the cartridge valve. Closed loopdepends on one or more sensors that are either internal or external tothe actuator. These sensors may be contact or contactless sensors,including linear variable differential transformer (LVDT), rotaryvariable differential transformer (RVDT), Hall effect, resolvers, analogwipers, etc.

Embodiments of the actuator may be configured with or without a shaftposition sensor. In the case of open loop control the shaft positionsensor is not required and the engine uses other sensors as well asmechanical hydraulic control valve force feedback to control theactuator and thus modulate the valve. In the case of closed loop controlthe shaft position sensor may be used for initial start-up calibrationor continuous control. As shown in FIGS. 17 and 19, the upper cover 802may include a cavity or recess 838 in which a sensor may be positioned.The cavity 838 may be covered or sealed by a cover 840. The cover 840may be secured to the upper cover 802 by screws 844 or other fasteners.Alternatively, the cover may itself have threads or engagement surfacesthat engage with corresponding portions of the upper cover 802.

Embodiments of the shaft position sensor can be of the standalone designwere position feedback is being monitored by a remote centralizedcontrol system or installed on a circuit board for actuator onboardcircuit design option for decentralized actuator/valve control system orhybrids thereof. In the case of standalone shaft position systems theshaft position sensor can be of the variable transformer, hall effect,magneto-resistive, inductive, capacitive, resistive, optic type orvariants of thereof. In the case of integrated shaft positions sensor,the sensor is integrated into the circuit board of the decentralizedcontrol system and can be of the many variants discussed above.

FIG. 4 depicts an embodiment of the invention that includes a butterflyfluid modulating valve 302 with a multi-vane actuator, single-multipartproportional spool valve and shaft position feedback. This assembly maybe monitored and controlled via remote controllers that can bestandalone actuator controllers but can also he part of the enginecontrol unit. This design has the disadvantage that electronic control,power and communication require large number of wires and complexelectric connectors. Depending on the feedback and communication 12wires or more are required. Such configuration suffers fromcommunication time lags, susceptible to electromagnetic interference andelectric wire/connector failure due to the harsh environmentalconditions existent in the engine compartment.

In another embodiment, the valve is designed to contain its owncontroller. The communication can be analog or digital. Analogcommunication can be of the voltage or current type and in the digitalcase it can be PWM (Pulse Width Modulated), or via CAN (Central AreaNetwork) and its variant. For industrial application these communicationcan be configured to use Ethernet, RS232, RS 485 and its other variants.This design option retains full actuator onboard control and onboarddiagnostics. The circuit board components are selected for harshenvironmental conditions and fully encapsulated to protect for coolingfluid exposure with the objective to protect the circuit from externaland cool the circuit internal heat being generated. The fullyencapsulated circuit board layout is configured to integrate allrequired major building blocks required for the control, protection anddiagnostics of the actuator and the connection points via compliant pinsto the input and output connections points for external or internalcommunications or control such as proportional solenoid valves. Theencapsulated circuit board would transfer its heat via thermallyconductive encapsulant or encapsulated heat sinks that are directly incontact with the cooling circuit.

The single layer or multilayer circuit board of such an embodiment ofthe actuator would contain all or part of the following main buildingblocks: microcontroller, a spool or poppet valve driver, circuitprotection, shaft position sensor and I/O connection points in the formof hard mounted connector or flying lead. These building blocks can begenerated using discrete components or highly integrated usingproprietary ASIC/FPGA technology. The package size of the circuit boardfits into machinable areas of 20 mm in diameter to 60 mm in diameter. Asshown in FIGS. 17 and 18 it may be installed to the upper cover 802 viascrews 844, clips or other retention mechanism commonly used in theindustry. Alternatively, the circuitry could be installed in the mainhousing 308 (see FIG. 4).

The actuator described herein may be referred to as a remote actuator.However, it will be understood that actuator can be remote but that,alternatively, its function and performance can also be built into theactuator or a valve associated with the actuator to reduce packaging andcost.

What is claimed is:
 1. A hydraulic rotary actuator, comprising: a fluidinput; a fluid output; a main housing comprising a cavity, the cavitycomprising a primary chamber and a secondary chamber; a first cover atleast partially covering a first side of the main housing, the firstcover comprising a cooling circuit formed in the first cover throughwhich a hydraulic fluid flows; a second cover at least partiallycovering a second side of the main housing, the second cover comprisinga cooling circuit formed in the second cover through which a hydraulicfluid flows; a rotational assembly positioned at least partly within thecavity of the main housing, the rotational assembly comprising: a hub, afirst vane that moves within the primary chamber in response to thehydraulic fluid flowing into the primary chamber to impart rotationalmotion to the rotational assembly, a second vane that moves within thesecondary chamber in response to the hydraulic fluid flowing into thesecondary chamber to impart rotational motion to the rotationalassembly, a first manifold providing a fluid connection between theprimary chamber and the secondary chamber, the first manifold extendingthrough at least a portion of the first vane and extending through atleast a portion of the hub spaced apart from the axis of rotation suchthat the first manifold does not intersect the axis of rotation, and asecond manifold providing a fluid connection between the secondarychamber and the primary chamber, the second manifold extending throughat least a portion of the second vane and extending through at least aportion of the hub spaced apart from the axis of rotation such that thesecond manifold does not intersect the axis of rotation; and amechanical connection that connects the rotational assembly to a deviceto be driven in rotational movement; wherein the vanes of the rotationalassembly are not evenly spaced around the axis of rotation, and whereinthe first and second manifolds are not in fluid communication.
 2. Thehydraulic rotary actuator of claim 1 wherein the first cover coolingcircuit is fluidly connected in parallel with the flow of the hydraulicfluid through the primary chamber.
 3. The hydraulic rotary actuator ofclaim 2 wherein the second cover cooling circuit is fluidly connected inparallel with the flow of the hydraulic fluid though the primarychamber.
 4. The hydraulic rotary actuator of claim 3 wherein the firstcover cooling circuit and the second cover cooling circuit are fluidlyconnected in parallel with the flow of the hydraulic fluid through theprimary chamber.
 5. The hydraulic rotary actuator of claim 1 wherein thefirst cover cooling circuit is fluidly connected in series with the flowof the hydraulic fluid through the primary chamber.
 6. The hydraulicrotary actuator of claim 5 wherein the second cover cooling circuit isfluidly connected in series with, the flow of the hydraulic fluidthrough the primary chamber.
 7. The hydraulic rotary actuator of claim 6wherein the first cover cooling circuit and the second cover coolingcircuit are fluidly connected in series with the flow of the hydraulicfluid through the primary chamber.
 8. The hydraulic rotary actuator ofclaim 1 wherein the first cover cooling circuit is not fluidly connectedwith the flow of the hydraulic fluid through the second cover coolingcircuit and is not fluidly connected with the flow of the hydraulicfluid through the primary chamber.
 9. The hydraulic rotary actuator ofclaim 1 wherein the first cover cooling circuit is fluidly connectedwith the flow of the hydraulic fluid through the second cover coolingcircuit, and the first cover cooling circuit and second cover coolingcircuits are not fluidly connected with the flow of the hydraulic fluidthrough the primary chamber.
 10. The hydraulic rotary actuator of claim1 wherein the second cover has a configuration that is symmetrical tothe first cover.
 11. The hydraulic rotary actuator of claim 11 where inthe first cover and the second cover are cast, forged, billeted orextruded.
 12. The hydraulic rotary actuator of claim 12 wherein a moldor die for casting, forging, billeting or extruding the first cover isthe mold or die for casting, forging, billeting or extruding the secondcover.
 13. The hydraulic rotary actuator of claim 12 wherein the firstcover is further processed to create an opening to accommodate at leastone of a sensor and other control circuitry.
 14. The hydraulic rotaryactuator of claim 12 wherein the second cover is further processed tocreate an opening to accommodate a shaft seal.
 15. The hydraulic rotaryactuator of claim 1 wherein the first cover comprises a cavity.
 16. Thehydraulic rotary actuator of claim 15 wherein the first cover comprisesa sensor positioned at least partially within the cavity.
 17. Thehydraulic rotary actuator of claim 16 further comprising a cavity coverthat at least partially covers the cavity.
 18. The hydraulic rotaryactuator of claim 17 wherein the cavity cover seals the cavity.
 19. Thehydraulic rotary actuator of claim 1 wherein the second cover comprisesan opening,
 20. The hydraulic rotary actuator of claim 19 wherein themechanical connection comprises a shaft, and the shaft extends throughthe second cover opening.
 21. The. hydraulic rotary actuator of claim 20further comprising a shaft seal, wherein the shaft seal is positioned atleast partially within the second cover opening, and the shaft sealseals against an outer surface of the shaft.
 22. A hydraulic rotaryactuator, comprising: a fluid input; a fluid output; a main housingcomprising a cavity, the cavity comprising a primary chamber and asecondary chamber; a first cover at least partially covering a firstside of the main housing, the first cover comprising: a cooling circuitformed in the first cover through which a hydraulic fluid flows, acavity, a sensor positioned at least partially within the cavity, and acavity cover that seals the cavity; a second cover at least partiallycovering a second side of the main housing, the second cover comprising:a cooling circuit formed in the second cover through which a hydraulicfluid flows, an opening, and a shaft seal; a rotational assemblypositioned at least partly within the cavity of the main housing, therotational assembly comprising: a hub, a first vane that moves withinthe primary chamber in response to the hydraulic fluid flowing into theprimary chamber to impart rotational motion to the rotational assembly,a second vane that moves within the secondary chamber in response to thehydraulic fluid flowing into the secondary chamber to impart rotationalmotion to the rotational assembly, a first manifold providing a fluidconnection between the primary chamber and the secondary chamber, thefirst manifold extending through at least a portion of the first vaneand extending through at least a portion of the hub spaced apart fromthe axis of rotation such that the first manifold does not intersect theaxis of rotation, and a second manifold providing a fluid connectionbetween the secondary chamber and the primary chamber, the secondmanifold extending through at least a portion of the second vane andextending through at least a portion of the hub spaced apart from theaxis of rotation such that the second manifold does not intersect theaxis of rotation; and a mechanical connection that connects therotational assembly to a device to be driven in rotational movement, themechanical connection comprising a shaft; wherein the vanes of therotational assembly are not evenly spaced around the axis of rotation,the first and second manifolds are not in fluid communication, and theshaft seat seals against an outer surface of the shaft.